I am experiencing the exact same error. Sometimes it is sporadic. At other times it consistently/repeatedly fails. When it fails, most admin functions (including publishing/updating posts) cease to function properly (they get terminated by the error before they can complete).
My only option has been to deactivate the plugin and I was only able to do that during one of the instances when the error did not occur (it took many attempts to successfully get into the Plugins page).
I would like to use this plugin; but, this error is a show stopper. Please help.